A balance-to-unbalance transformer (balun) comprising a first signal input/output with two symmetrical poles, a second signal input with one pole, several first conductor loop regions, which are located between the two poles of the first signal input and the ground and a second series connection of several conductor loop regions, the first terminal of the latter being connected to the pole of the second signal input. Two second conductor loop regions are electromagnetically coupled to a respective conductor loop region. The second outer terminal of the second series connection of several second conductor loop regions is electrically connected to the intermediate terminal of a first series connection of several first conductor loop regions, which connect a symmetrical pole of the first signal input to the ground.